This invention relates to a transgenic animal model for testing immunogenicity and protective efficacy of human vaccines as well as a method for generating such a multi-transgenic animal. This invention also relates to methods for screening compositions for human vaccine development. More specifically, the present invention relates to a mouse model capable of expressing human leukocyte antigen DR4, and human costimulatory molecules (CD80) upon infusion of human HLA-matched hematopoietic stem cells, which reconstitute long-lived and functional human T and B cells.
Human vaccine research often requires in vivo analysis to test the immunogenicity, protective efficacy, and toxicity of certain vaccine candidates. However, in vivo human study is severely limited due to ethical and technical constraints. There is a growing need for an animal model to carry out in vivo studies of human cells, tissues and organs, without putting individuals at risk. Many important studies have been carried out using mice as an animal model in research of complex human biological systems. There is a growing need of “humanized mouse model” capable of reconstitute a surrogate human immune system (HIS) that can be used for studies on human immunology, which may provide a predictive preclinical model for human vaccines prior to clinical trails.
Various models of humanized mice were developed with different genetic manipulations designed to meet the needs of in vivo studies of human systems. (See Table 1). Although, the current mouse models permit long-term hematopoiesis of human B cells (2, 3). they allow poor development of functional human T cells (2-5). The current mouse models also fail to develop serum levels of human IgM and IgG comparable to that of human blood (3). This limitation has been attributed to the lack of expression of Human Leukocyte Antigens (HLA) molecules in mouse lymphoid organs. Recently, humanized mice expression HLA class I molecules have been generated but shows little improvement in human T cell reconstitution and function of T and B cells (6. 11.12). Upon vaccination, infection, or transplantation, current humanized mouse models fails to elicit immune responses in the same extent as vaccinated or infected humans (2-5. 7-9). A humanized mouse model, or a mouse-human chimera, which overcome these constraints, is described in the instant application, and in Danner R. Chaudhari SN. Rosenberger J. Expression of HLA class II molecules in humanized NOD.Rag1 KO.IL2RgcKO mice is critical for development and function of human T and B cells. PLoS One. 2011:6(5):e19826, is incorporated herein by reference in its entirety.
TABLE 1Current Humanized Mouse ModelsMutate allelePhenotypeAdvantageDisadvantageNOD-scid KONo mature T and B cellslow level of innate immunityResidual innate immunityRadiation sensitivelow NK-cell functionLow but present NK-cellDecrease innate immunityincreased engraftment ofactivityhuman HSCs and PBMCsDecrease lifespan owing tothymic lymphomasNOD-scid KO,No mature T and B cellsLong lifespanLack appropriate MHCIL2Rγ KORadiation sensitiveFurther reduction in innatemolecules for T-cell selectionIL-2Rγ-chain deficiently; noimmunityin the mouse thymushigh-affinity signalingNK cells absentSeem to lack some human-through multiple cytokineHigher level of engraftment ofspecific cytokines required forreceptors leading to manyhuman cellshuman cell development andinnate-immune defectsDevelop functional humansurvivalimmune systemLow and variable level of T-Complete absence of IL2rgcell-dependant antibodygeneresponsesNOD-Rag1 KORag1 mutation leading toRadiation resistantResidual innate immunitylack of mature T and B cellsLow but present NK-cellactivityLow and Variable level ofengraftmentNOD-Rag1 KO,Rag1 mutation leading toRadiation resistantIL2Rγ KOlack of mature T and B cellsLong lifespanIL-2Rγ-chain deficiently; noFurther reduction in innatehigh-affinity signalingimmunitythrough multiple cytokineNK cells absentreceptors leading to manyHigher level of engraftment ofinnate-immune defectshuman cellsDevelop functional humanimmune systemComplete absence of IL2rggeneNOD-scid, HLA-A2,Transgenic expression ofLong lifespanSeem to lack some human-IL2Rγ KOhuman HLA-A2Further reduction in innatespecific cytokines required forNo mature T and B cellsimmunityhuman cell development andRadiation sensitiveNK cells absentsurvivalIL-2Rγ-chain deficiently; noHigher level of engraftment ofLow and variable level of T-high-affinity signalinghuman cellscell-dependant antibodythrough multiple cytokineDevelop functional humanresponsesreceptors leading to manyimmune systeminnate-immune defectsComplete absence of IL2rggeneTransgenic expression ofhuman MHC moleculesBALB/c-Rag1 KO,Rag1 mutation leading toRadiation resistant (can surviveResidual innate immunitylack of mature T and B cellshigh dose of radiation)Low but present NK-cellactivityLow and variable level ofengraftmentBALB/c-Rag1 KO,Rag1 mutation leading toRadiation ResistantIL2Rγ KOlack of mature T and B cellsIL-2Rγ-chain deficiently; nohigh-affinity signalingthrough multiple cytokinereceptors leading to manyinnate-immune defects